다양한 식이가 요각류 Tigriopus japonicus의 insulin-like peptide (ILP)의 발현에 미치는 영향

Abstract

Insulin-like peptide (ILP) is one of important hormone in invertebrates to control glucose level in body fluids. However, ILP was not reported in copepods as yet. To better understand a role of the copepod ILP in relation to dietary metabolism, the copepod Tigriopus japonicus insulin-like peptide (Tj-ILP) was firstly isolated in copepods, characterized with conserved motifs, and measured its transcriptional modulation in response to different sources of carbohydrate. The full-length Tj-ILP cDNA was 525 bp in length, encoding 174 amino acid residues. Multiple alignments revealed that six conserved cysteine residues in the ILP peptide domain were conserved for maintaining tertiary structure and its function. To check as to whether the transcriptional expression of Tj-ILP gene can be modulated by different carbohydrate sources, two simple sugars (glucose and sucrose) and food supplies (Chlorella vulgaris and Tetraselmis suecica) were provided to copepods, and dose- or time-dependency of Tj-ILP mRNA expression was analyzed in feeding or non-feeding condition. In response to simple sugar treatments, Tj-ILP transcripts were not modulated up to 50 g/L, while its transcriptional level was significantly elevated by both algal food supplies.